Heating apparatus



July 7, 1942. B. GOERG 'HEATING APPARATUS Filed Deo. 1'?, 1938 2 Sheets-Sheet l ummm MTHHIMN.-

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INVENTOR July 7, 1942.

Filed Dec.A 17, 1938 2 sheets-sheet 2 Patented July 7, 1942 UNITED' STATES PATENT OFFICE HEATING APPARATUS Bernard Goerg, Tuckah-oe, -N. Y., assignor, by mesne assignments, to American Radiator & Standard Sanitary Corporation, New York, N. Y., a corporation of Delaware Application December 17, 1938, Serial No. 246,273

1l) Claims.

4My invention relates to heating apparatus and more particularlyto boilers adapted to be fired by a fuel burning mechanism operating with forced draft; such, for example, as a boiler red by a mechanical Stoker.

An object of this invention is to provide a boiler of the above type which is of improved construction and arrangement of parts and one which provides for the efficient combustion of the fuel.

A further object is to provide a boiler adapted to be heated by mechanism burning solid fuel under forced draft, wherein provision is made for effectively burning out combustible matter in the combustion gases prior to entering the boiler iiue.

A further object is to provide a boiler of the above type wherein provision is made for separating fly ash from the combustion gases prior to entering the boiler iiue.

The invention consists in the novel construction and combination of parts, to be more fully` described hereinafter, and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawings, to be taken as a part of this specication, I have fully and clearly illustrated a preferred embodiment of my invention, in which drawings: f

Fig. l is a longitudinal vertical section through a boiler constructed in accordance with the present invention;

Fig. 2 is a transverse vertical section taken on the line 2-2 of Fig. 1 and looking toward the front of the boiler; and

Fig. 3 is a transverse vertical section taken on the line 3 3 of Fig. l and looking toward the rear of the boiler.

Referring now in detail to the preferred embodiment of my invention which I have elected to disclose, it will be observed that I have shown my invention as embodied in a boiler Il), which is formed by a plurality of hollow cast-,metal sections arranged in vertical side-byeside relation. As shown, the boiler is advantageously composed of a front section I I, a rear section I2, a plurality of full-size intermediate sections I3, a half-size bridge wall section I4, a half-size intermediate section I5 behind the section I4, and a half-size baffle wall section I6 between the section I5 and rear section I2. Each of the boiler sections may be formed as a one piece casting with hollow interior spaces providing a water space I1 and steam spaceI I8 for the boiler. The sections are joined at each side of their bottom by nipples I9 Cil and at their top and center by nipples 20, so as to provide for the circulation of boiler Water between sections and for the accumulation of steam from all'sections in the steam space I8 which is common to all sections..

The boiler I0 is advantageously provided with a brick supporting base 23, which includes a transverse front wall 24 beneath andsupporting the `front section II, a transverse intermediate wall 25 beneath and supporting the bridge wall section I4, and a transverse rear wall 26 beneathV and supporting the rear section I2.A The base 23 also comprises longitudinallyfextending side walls 21 supporting, respectively, the sides of the several sections and rjoining the ends of the front Wall 24, intermediate wall 25, and rear Wall 26. The assembled boiler sections are encased in a sheet metal jacket 30 of pleasing appearance, and the brick base is enclosed in a sheet metal skirt 3| which overlaps at its upper end .the lower part of the jacket, to provide a neat and finished apfpearance to the lower` part of the boiler.

The several sections of the boiler are so constructed that they provide, when assembled, a combustion chamber 34 dened by a front wall 35 formed by the lower part of the section II, side walls 36 formed by the lower part of the water legs of sections.` I 'I and I4, and a top Wall or crown sheet 3l also formed by the sections II and I4 and in part by the sections I5 and I6. A hollow bridge Wall 38, which is' a part of the section I4, extends across the rear of the com- .usual underfeed lire pot 4I wherein `the coal is burned and the air is supplied under force draft; a coal feed tube 42 connected at one end to the lower part of the pot 4I and extending outwardly of the boiler through aligned openings in the wall 24 and skirt 3| and a coal hopper 43 connected at its lower end to the outer end of the tube 42. The several elements Vof the Stoker, as just described, are shown as being typical of the mechanical stokers available on the market; it being understood that, in so far as certain of the broader aspects of my invention are concerned,

any other type of stoker or forced draft grate construction may be used.

Arranged at the rear of the bridge wall 38 and formed as a part of the casting I6, is a depending baffle wall 45 formed hollow and containing the boiler water which circulates therethrough. The baflle wall 45 and the bridge wall 38 denne a down-flow ue 46 which is connected at its upper end to the gas outlet opening 39, and is connected at its lower end to the lower end of an up-flow flue 41. The up-flow flue 41 is defined by the rear surface of the baille wall 45 and the inside or forward surface of the rear section I2, and is connected at its upper end to the inlet end of a boiler liue 49 formed by the assembled boiler sections. The boiler flue 49 extends horizontally and forwardly towards the front of the boiler, where it makes an abrupt 180 turn, and then extends rearwardly towards the back of the boiler and connects at its rear outlet end with a smoke outlet boX D.

The down-ow passage 45 and up-flow passage 41 provide an upright U-shaped flow path for the combustion gases connecting the combustion chamber with the boiler flue. The arrows in Fig. 1 indicate the ow path for the combustion gases through the boiler. Beneath the return bend of this U-shaped flow path, is provided an ash settling chamber 52, the latter being defined by the walls 25, 26, and 21 of the brick supporting base 23. One of the walls 21 is provided with an opening 53, and an opening 54 is provided in the skirt 3i which is aligned with the opening 53. The openings 53 and 54 provide for the removal of ash from the chamber 52, and doors 55 and 55 serve, respectively, to close these openings.

Should the Stoker iii be operated with a soft coal, the combustion gases leaving the chamber 34 will, under certain conditions of operation, contain a certain amount of combustible matter such as carbon monoxide (CO) smoke, etc., and will also contain a certain amount of ily ash lifted off of the pot 4l by the forced air draft. Also, under certain conditions of operation, the air currents will lift small solid particles of coal undergoing combustion, and cause them to be carried in suspension in the out flowing gas stream. Fly ash is also present in boilers burning hard coal under a forced draft. If no provision is made for burning out the combustible matter which either forms a part of or is carried in suspension in the gas stream, a low efficiency of combustion results. Furthermore, if the fly ash is not removed from the gas stream, it will settle in the boilerflues and interfere with efficient heat transfer to the boiler water. If the fly ash is permitted to collect on surfaces traversed by the hot combustion gases immediately adjacent the combustion chamber, small particles of coal burning in suspension will deposit molten ash on the collected ily ash and thereby build up a clinker formation which will interfere with gas flow, combustion, and proper heat transfer to the boiler water. A further condition to be met in any furnace where the fuel is burned by forced draft, is the torch-like flames which sometimes are present and which play on the crown sheet or top wall of the combustion chamber and will result in damage to the wall, if it is not protected.

From the above description, it will be apparent that my improved boiler construction effectively solves the problem of preventing fly ash from settling in the boiler flues of boilers fired by forced draft stokers or grates. 4In my construction, any fly ash entrained in the gas stream leaving the combustion chamber will be separated out of the gas stream at the bottom of the down-flow ue 46, due to the change in direction of flow of the gases at this point from downward to upward. The separated y ash will settle in the chamber 52 and can be readily removed through the openings 53, 54, as previously described.

In order to provide for the burning out of combustible matter in the gas stream, the combustion gases are caused to flow over a relatively long flow path, and the temperature of the combustion gases is maintained, while flowing over this long path, at a value above the ignition temperature of the combustible therein. This is effected in the present construction by covering the underside of the top wall 31, the forward side of the baille wall 45, and the rear surface of the bridge wall 38 with heat-resistant steel plates 63, 6i, on which fly ash cannot collect and the plates 82, respectively. The plates provide a smooth contact surface for the combustion gases and are protected from burning out by their proximity to the water cooled surfaces of the walls 31, 45, and 38. In order to prevent the temperature of the plates from being cooled by heat transfer to the boiler water, below a point where the gas would be chilled below the ignition temperature of the combustible in the gas stream; the plates are spaced from their respective water cooled walls a slight distance. The spaces between the plates and the water cooled surfaces reduce heat transfer from the plates to the boiler water by conduction, yet the transfer from the plates to the boiler water by radiation is sufficient to protect the plates from damage by the hot gas stream. Thus, the height of the combustion chamber 34 coupled with the length of they down-flow ue 4S provides the desired long flow path for the combustion gases which is kept hot by the plates iiD, 5I, and 32 and provides for the burning out of the smoke. If desired, secondary air may be admitted through a door 63 in th'e front wall 35.

It is to be understood that, in so far as certain of the aspects of my invention are concerned, the plates (iii, 6I, and S2 maybe constructed of any suitable metal providing a smooth contact surface for the gases and which will effectively sta-nd up under temperatures ranging upward to 20G0 F. An example of such a metal is a heatresistant alloy steel plate containing a percentage of chromium and, if desired, a percentage of nickel, such steel being available on the open market. The plates are preferably of such a size that they may be inserted and removed through door 63, thereby permitting the removal of the plates without requiring a special opening for that pufpose. The heat-resistant steel plates are admirably suited for the purposes described, as they can be easily shipped and handled without breaking; can be bent around corners in assembling them in a boiler and will then spring back into shape; are relatively light in weight and are thin, thereby occupying a minimum of space in the boiler; and lastly, will stand up under high temperatures for long periods of time.

The plate El! is secured to the top wall 31 by screws 65. Due to the contour of the underside of the top wall 31, the plate lili only touches the wall at the lowermost edges of the several boiler sections forming the top wall 31. Thus, the transfer of heat by conduction is reduced to that provided by this limited area of contact, and the plate 60 is kept at the required temperature. In addition to the above advantages, the plate 60 also prevents the torch-like flames, which sometimes occur in a forced draft fuel burner, from contacting and damaging the crown sheet or top wall 31 of the boiler.

The plate 6l, which covers the forward surface of the baffle wall 45, is held in position by lugs 68 extending forwardly from the lower part of the wall 45 and which are shaped to embrace and support the lower edge of the plate 6|, and by hook-like lugs 69 extending from the upper part of the wall 45 and through openings 10 in the plate E I. In order to keep the plate spaced from the wall 45 the proper distance to prevent chilling below the required temperature, a plurality of spaced projections 1I of even length extend from the forward surface of the wall 45 and engage the rear surface of the plate 6I. In the construction shown, the projections 'Il provide a space from 1/8 to ,-36 of an inch between the plate andbaflie wall. The plate 6I is secured in place against one of the projections 'H by a screw 12,

The plate B2 which covers the rear surface of the bridge wall 38, is supported at its lower edge on the wall 38 by rearwardly extending lugs 74. The upper end of the plate 62 is bent to provide a downwardly facing channel part 15 which ts over and embraces the top edge of the bridge wall 33 and is secured to the latter by screws 16. The plate 62 is spaced the proper distance from the rear surface of the bridge wall b-y projections 11 of even length extending rearwardly from the wall 38 and engaging the forward inner surface of the plate 62. The projections 1l also provide a space between the plate and the wall from 1/8 to of an inch.

As stated previously, the spacing of the plates 6d, El, and 62, and the limiting of the areas of contact between the plates and the water cooled walls to widely spaced points, results in the plates being maintained at a temperature which will prevent the chilling of the colnbustion gases below the ignition temperature of the combustible matter in the gases before such combustible matter is burned out; and the transfer of heat from the plates to the boiler water by radiation and by conduction at the spaced points vof contact, results in the cooling of the plates l below a point where they will be damaged. This transfer of heat from the plates to the boiler water also increases the boiler capacity. A further and important point is that suiiicient heat is transferred from the plates to the boiler water to maintain the plates at a temperature below the fusion temperature of ash. Therefore,4

any molten ash resulting from the burning of small solid particles of fuel in suspension in the gas stream, will be chilled and fall away from the smooth plate surface and thereby prevent the building up of clinker on the plate surfaces. The fusion temperature of ash is different for each particular type of coal burned, and it can be easily determined by accepted test methods known to those skilled in the art. For practical purposes, it is believed to be safe to assume that the ash fusion temperatures of any of the commercial coals will not fall materially below 18G0 F., and for the great majority of these coals, the ash fusion temperatures will be substantially higher than 1800 F. Furthermore, as ,the contact surface of the plates are smooth, no fly ash can collect thereon in such a manner as to provide an outer contact surface of iiy ash for the combustion gases, which surface would be above the fusion temperature of ash and would result in molten ash in suspension in the gas stream sticking to the fly ash and thereby building upa clinker formation.

What I claim and desire to secure by Letters Patent of the United States is:

l. A boiler comprising hollow walls defining a combustion chamber, a boiler flue pass, and a combustion gas passage connecting the combustion chamber and boiler flue pass; the surface of said walls being cooled by boiler water circulating through the hollow interior spaces thereof; and a pair of heat-resistant steel plates lining respectively opposed cooled surfaces of said combustion gas passage and forming smooth contact surfaces for the combustion gases leaving said combustion chamber; said plates being spaced from their adjacent water-cooled surfaces in such a manner that the temperature of the surfaces of the plates will be sufficiently high to prevent cooling of the combustion gases below the ignition temperature of the combustible content thereof yet sufcient heat is given up by the plates to the adjacent water-cooled wall surfaces to provide a plate surface temperature lower than the fusion temperature of molten ash particles in suspension in the combustion gases.

2. A boiler comprising walls defining a combustion chamber having provisions for combustion of solid fuel under forced draft and including an upright water-cooled bridge wall arranged across the rear thereof and providing a combustion gas outlet at the upper rear part of the combustion chamber; an up-right hollow watercooled baffle wall spaced rearwardly from said bridge wall and defining with its forward surfaces and with the rear surfaces of said bridge wall, a down-flow flue for combustion gases connected at its upper end to said gas outlet; said baiiie wall defining with its rear surfaces an up-flow flue connected at its lower end to the lower end of said down-fiow iiue; said boiler being provided with a flue pass having an inlet connected with the upper end of said up-fiow flue; a first heat-resistant steel plate covering a substantial portion of the water-cooled rear surface of said bridge wall and spaced slightly therefrom; and .a second heat-resistant steel plate covering a substantial portion of the watercooled forward surface of said baiiie wall and spaced slightly therefrom and defining with said iirst steel plate smooth contact surfaces for said combustion gases.

3. A boiler comprising water-cooled metallic walls defining a combustion chamber having provisions for the burning of solid fuel under forced draft, an ash-separating iiue, and a boiler flue, with the chamber, ash-separating flue and boiler iiue connected for series flow of combustion gases; the defining walls of said combustion chamber providing a combustion gas outlet opening in the upper and rear part thereof; the water-cooled defining walls of said ash-separating flue being constructed and arranged to provide an upright U-shaped path for liow of` combustion gases with one leg of the U connected at its upper end to said gas outlet opening and the other leg of the U connected at its upper end to the inlet of said boiler flue; means at the lower end of said U-shaped path for removing fly ash separated out of the gas stream; and heat-resistant steel plate members connected respectively to and spaced a slight distance from opposed inner surfaces of the water-cooled walls defining said one leg of the U, so as to provide smooth contact surfaces for the gas which are maintained sufliciently hot to prevent chilling of the gas stream below the ignition temperature of combustible therein and sufficiently cool to prevent molten ily ash from adhering thereto.

4. A boiler comprising means defining a combustion chamber for burning solid fuel under forced draft and including side walls, a top wall, and a rear hollow bridge wall extending between the side walls and terminating at its upper end short of the top wall to provide an outlet for combustion gases; a hollow baffle wall depending from the top wall at the rear of the bridge wall and defining therewith a down-flow flue for combustion gases connected at its upper end to said outlet; said bridge and baifle walls being cooled by boiler water circulating therethrough; means defining an up-iiow passage connected at its lower end to said down-flow passage; means defining a boiler flue pass having an inlet connected to the upper end of said upflow passage; means at the lower connected endsv of said down-flow and up-flow passages for removing fly ash separated out by change in direction of now of the combustion gases; and a pair of heat-resistant steel plates covering, respectively, a substantial portion of the rear surface of said water-cooled bridge wall and the forward surface of said water-cooled baliie wall to provide smooth contact surfaces for the combustion gases, and being spaced, respectively, a slight distance from their adjacent water-cooled surfaces to maintain a plate surface temperature above a point where the combustion gases would be cooled below the ignition temperature of the combustible therein, and below a point where molten ash would adhere thereto.

5. A boiler comprising means defining a combustion chamber for burning solid fuel under forced draft and including side walls, a hollow top wall, and a hollow rear bridge wall extending between the side walls and terminating at its upper end short of the top wall to provide an outlet for combustion gases; a hollow baffle wall depending from the top wall at the rear of the bridge wall and defining therewith a downow flue for combustion gases connected at its upper end to said outlet; said, top, bridge, and baille walls being cooled by boiler water circulating therethrough; a heat-resistant steel plate covering a substantial portion of the under surface of said water-cooled top wall and secured thereto at spaced points to provide a smooth contact surface for the combustion gases; and a pair cf heat-resistant steel plates covering, respectively, a substantial portion of the rear surface of said water-cooled bridge Wall and the forward surface of said water-cooled baiile wall to provide smooth contact surfaces for the combustion gases; all three of said plates having most of their surfaces spaced from their respective water-cooled walls in such a manner that the plates are not cooled by heat transfer to the boiler water to a temperature where they chill the combustion gases below the ignition temperature of combustible in the gases.

6. A boiler comprising water-cooled metallic walls defining a combustion chamber in which solid fuel is adapted to be burned under a substantial draft; said walls also defining an ashseparating iiue and a boiler flue, and said combustion chamber, said ash-separating flue and said boiler flue being arranged and connected together for series flow of combustion gases; the portion of said walls which define said ashseparating flue being formed hollow to provide for the circulation of water therethrough and being so constructed and arranged that said ashseparating flue provides a U-shaped flow path for the combustion gases with an inlet leg of the U having an inlet end communicatively connected with said combustion chamber and an outlet leg of the U having an outlet end communicatively connected with said boiler flue; means at the bend of said U-shaped flow path for collecting fly ash separated out of the gas stream by change in the direction of flow 0f the gases; and heat-resistant steel plate members covering inner water-cooled surfaces of the walls defining said inlet leg of the U, and being spaced respectively from said surfaces in such a manner that the surfaces of said plate members contacting the gas stream are maintained sufficient- 1y hot to prevent chilling of the gas stream below the ignition point of combustible therein and at a temperature below the fusion point of ash.

, '7. A boiler comprising wall structure defining a combustion chamber adapted to include means for burning solid fuel under forced draft and having a combustion gas outlet; said wall structure also defining a boiler flue and a combustion gas passage connecting said gas outlet with the boiler flue; said gas passage being of a length sufficient to provide for the burning of combustible matter in the combustion gases flowing therethrough; at least a part of said wall structure which defines the portion of the gas passage adjacent said gas outlet, being formed with a hollow interior to contain boiler water; and a heat-resistant steel plate covering said hollow wall part to prevent the gas stream from contacting said hollow wall part and to provide a smooth contact surface for the combustion gases, and said plate being spaced a slight distance from said hollow wall part so that at least the maior portion of the heat passing from said plate to said hollow wall part will be transmitted by radiation, thereby assuring a hot gas Contact surface which prevents undue chilling of the combustion gases, and at the same time providing for sufficient heat transmission from said plate to protect the plate and prevent the sticking of molten ash thereto.

8. In a boiler of the cast-metal sectional type having a combustion chamber in which solid fuel is adapted to be burned on a fuel bed, a hollow wall section so located as to be in the path of burning combustion gases leaving such fuel bed and adapted to contain boiler water; and a heatresistant steel plate covering said wall section to prevent the combustion gases from striking said section and providing on the side thereof away from said section a smooth contact surface for such gases, and said plate being spaced a slight distance from said hollow section so that at least the major portion of the heat passing from said plate to said section will be transmitted by radiation, thereby assuring a hot contact surface which prevents undue chilling of the combustion gases, and at the same time providing for sufficient heat transmission from said plate to protect the plate and prevent the sticking of molten ash thereto.

9. In a boiler of the cast-metal sectional type having a combustion chamber in which solid fuel is adapted to be burned on a fuel bed, a hollow wall section so located as to be in the path of burning combustion gases leaving such fuel bed and adapted to contain boiler Water; said Wall section being provided with spaced relatively short projections extending outwardly from the exterior surface thereof next to the stream of gases; and a heat-resistant steel plate covering said Wall section and engaging on one side thereof said projections and providing on the other side thereof a smooth contact surface for the gases, said projections being of such a length that said plate is spaced from said section so that at least the major portion of the heat passing from said plate to said section will be transmitted by radiation, thereby assuring a-hot contact surface which prevents undue chilling of the combustion gases, and at the same time providing for suicient heat transmission from said plate to protect the plate and prevent the sticking of molten ash thereto.

10. In a boiler of a cast-metal sectional type having a combustion chamber in which solid fuel is adapted to be burned on a fuel bed, a hollow wall section so located as to be in the path of burning combustion gases leaving such fuel bed and'adapted to contain boiler Water; and said section being provided on the exterior surface thereof which is arranged next to the combustion gas stream With spaced relatively short and outwardly extending projectionmand also being provided With a plurality of support-' ing lugs; and a heat-resistant steel plate covering a substantial portion of said section and being supported by said lugs and engaging on one side thereof said projections and providing on the other side thereof a smooth contact surface for the combustion gases; said projections being of such a length that said-plate is spaced from said section so that at least the major portion of the heat passing from said plate to said section will be transmitted by radiation, thereby assuring a hot contact surface which prevents undue chilling of the combustion gases, and at the same time providing for sufficient heat transmission from said plate to protect the plate and prevent the sticking of molten ash thereto.

BERNARD GOERG. 

